Data from several cancer screening studies are being collected and analyzed to gain a better understanding of the impact and consequences of such screening in various population settings, and to develop new techniques for data analysis. Results from the Health Insurance Plan of New York breast cancer screening trial continue to indicate a reduction in breast cancer mortality. The long term follow-up phase of the study is nearing completion. A trial of the Hemoccult test for blood in the stool for early detection of colorectal cancer is in progress. The working group on cervical cancer screening of the IARC analyzed data from screening programs in Scandinavia, Scotland, Canada, and Italy on the incidence rates of cancer after negative screens, Results indicate that the maximum achievable reduction in risk is about 90 percent with annual screening starting at age 20. The screening evaluation project of the UICC concluded that screening for cervical cancer every three years provides practically the same benefit as annual screening and that the same screening frequency should be used irrespective of age. Two occupational high risk groups are under scrutiny. In collaboration with DCE, the bladder cancer screening program at the DuPont Company is being analyzed to relate disease characteristics and outcome to urine cytology and blood tests, smoking history and chemical exposure. With DCE, and NIOSH updated follow-up data are being collected in a study of sputum cytology screening for lung cancer among uranium miners. The relationships among cytology classification, radiation exposure, smoking history, lung cancer, and mortality data will be analyzed.